Flood Hazard News
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Flood Hazard News Vol. 35, No. 1 December, 2005 A Brief History of the Walled Section of Cherry Creek By Mark Hunter, PE: Bill DeGroot, PE and Dave Lloyd, PE Robert Speer was elected Mayor of expressed concern about the leakage visible at the Kennedy Golf course. Denver in 1904. His administration and flood safety of the structure. One of began a period of dramatic civic the primary issues with Castlewood Flood control specialists quickly improvement including efforts to Dam was the fact that this on-stream recognized the inadequate capacity of control flooding on Cherry Creek. reservoir served its irrigation purposes Kenwood Dam and by 1940 federal Between 1906 and 1911 parallel best when it was full of water. This left agencies were planning its replacement concrete walls 10 feet tall and 80 feet little room for floodwater storage and with what would become the current apart were constructed from Downing meant that the spillway system was Cherry Creek Dam. Land was acquired Street to Blake Street to contain Cherry regularly called into use. in 1946 and by 1950 the new structure Creek. The termination of the walls at was in operation. In mid-June 1965 the Blake Street left the lower half-mile of The fear of the residents of Denver Cherry Creek Dam proved its worth Cherry Creek uncontained. became reality in early August, 1933 when it impounded the largest flood in when a series of summer the area's history while the uncontrolled The flood of July 14, 1912 inundated thundershowers completely filled the South Platte River delivered an the lower portion of the city and put reservoir, overtopped the dam, and unprecedented flood to Denver. three feet of water in Union Station. eventually breached the structure. The impact of this flood hastened the Thirty five miles downstream in Denver In the years that followed, the channel completion of the concrete walls the the flood tore out some of remainder of the way to the South Platte the concrete channel River. With the flood of 1912 still in walls, and put a foot of mind the dimensions of the walls were water on the floor of increased to a height of 12 feet and a Union Station. width of 88 feet. This final section was completed in 1914. These walls are still The 1933 flood forced in service and provide a continuous the City of Denver to walled channel for Cherry Creek for the develop a comprehensive 3.2 miles from Downing Street to the flood control plan for South Platte River. Cherry Creek. This local effort resulted in the Castlewood Dam was constructed on construction of Kenwood Cherry Creek just south of Franktown in Dam beginning in 1935. 1890 by a private organization for the It was located near the purpose of providing irrigation water. intersection of Hampden Ownership of the dam changed several Avenue and Havana times over the years but its purpose was Street just downstream of always to support the development and the current Cherry Creek sale of irrigated farm and ranch land in Dam. A few remnants of Douglas County. Observers the concrete components downstream in Denver quickly of Kenwood Dam are still The 1933 flood in the walled section of Cherry Creek fell into disrepair, heavily overgrown maintenance/recreation trail. with vegetation and a dumping ground However there were two areas for broken concrete, asphalt and other where the plan proposed debris. It was an eyesore, had lost much removing the walls to create of its flood carrying capacity, and was expanded park areas extending certainly no asset to the community. from creek level to street level. One site was at approximately In 1975 the Urban Drainage and Flood Larimer Street to Lawrence Control District, City and County of Street, and the other was near Denver, City of Glendale and Arapahoe the confluence with the South County embarked on an ambitious effort Platte River. Ultimately a to master plan the Cherry Creek corridor version of the former was from the South Platte River to Cherry constructed (see below) but Creek Dam. The master plan was to the other site was lost to new include flood control, recreation and development. transportation. The consulting team of Merrick and Co. and Harman, In the early 1980’s the City O’Donnell & Henninger Associates and County of Denver (HOH) was selected by the sponsors to received discretionary Federal develop alternative scenarios, seek grant money, and then Mayor public input, and prepare a master plan Bill McNicholls allocated for the corridor. these funds to implementation of the flood control and trail Transportation issues ultimately could plan in the walled section of not be resolved to the satisfaction of the the creek. This construction three local government sponsors, and, in effort provided the basic order to get the flood control and channel, trail and access ramp Top. Artist’s concept from the master plan. recreation elements of the plan configuration that would form Bottom. The channel following initial completed, the transportation portion the framework for several construction. was dropped. subsequent projects which are described below. The flood control study revealed that primarily boulder edging but also even with Cherry Creek Dam Two design decisions were made that included riprap protection and a couple constructed upstream, a large 100-year led to the need for later adjustments. sections of interlocking articulated flood hazard area existed through the The first was to take the trail out of the concrete blocks. By 1991 low flow neighborhoods adjacent to the walled bottom of the creek for stretches of channel protection was in place on section, including the Country Club several blocks where no traffic conflicts about 34% of the 3.2 miles of the walled neighborhood areas of downtown, and existed, in order to keep some areas of section of Cherry Creek. portions of the new Auraria campus. A the channel bottom more natural for major goal of the study became to wildlife habitat. However, walkers, In 1989 a bond issue was passed by the contain the 100-year flood to the runners and bicyclists quickly decided Denver voters which included funding channel. to stay in the bottom and wore trails for the urban redevelopment of Cherry through the intended habitat. In 1982 Creek from Colfax Avenue downstream The master plan was completed in 1977. the two gaps in the Cherry Creek trail to Market Street. This project became a Within the walled section the plan corridor where filled. About 3000 feet public/private partnership when the called for cleaning out the vegetation of eight foot wide concrete was installed Downtown Denver Partnership and the and debris, reshaping the bottom of the to complete the trail corridor within the Urban Drainage and Flood Control channel, installing a number of drop walled section of the creek. District joined Denver in the effort. The structures to control the channel grade, resulting project, known as CreekFront, and installing a number of access ramps The other decision was to not line the revitalized Cherry Creek as an urban and a maintenance access trail that low flow channel. Over time we began greenway while preserving the flood would also be used as a recreational to see severe erosion and migration carrying capacity. The project included trail. Two stair cases were also problems and had to address those two drop structures, including one included. problems with bank stabilization formal grouted boulder drop, a second measures as a function of the District’s (Continued on page 5) Most of the other proposed park Maintenance Program. Six phases of improvements involved new parks low flow channel bank protection were outside the channel walls but close to completed by the Maintenance Program the creek, and connected to the between 1984 and 1991. This work was 2 Lloyd’s Look by Dave Lloyd Timely Comment from the District's Executive Director How fortunate we are to live in the State for the purpose of enhancing the United Competition for the every decreasing of Colorado. This has never been more States's resilience and reducing our tax dollar is always a daunting task for in evidence than over the past year as vulnerability to natural and flood control managers. we've witnessed several natural technological hazards. disasters of epic proportions. Even though the Katrinas and Ritas of As was evidenced along the gulf coast, this past year go a long way in keeping I was just recently reading the cover our communites are still challenged by us focused upon the arena of sound story in the November 2005 issue of disaster preparation, response and floodplain management, mankind has "Natural Hazards Observer." The recovery. Although lives lost to natural always proven itself to have a short article points out that in the last year disasters each year have been reduced, memory (he says as he sits here trying alone, we've experienced a multitude of the annual cost of major disasters to remember what he had for breakfast). disasters including winter storms, continues to rise. The Subcommittee on wildfires, floods, tornadoes, landslides, Disaster Reduction identified four key In the words of Paul Danish, former and most recently Hurricanes Dennis, characteristics of disaster-resilient Boulder County Commissioner and Katrina, and Rita. Although not directly communities: Director on the District's Board when affecting the United States, the • Relevant hazards are asked if a devastating flood could occur earthquake and tsunami in the Indian recognized and understood one day along Boulder Creek: "Not Ocean last December claimed over • Communities at risk know only yes, but hell yes." 240,000 lives across 12 countries and when a hazard event is injured, displaced or otherwise impacted imminent Organizational and Staff Changes millions.